Would it be possible to use an LM13700 for the Transc. op-amps and some kind of transistor pair for the Exponential function converter? I am trying to breadboard this filter but I am stuck on the converter.

Does any one know a simple Anti log function generator circuit?
I found this(see pic) but I am not sure if this one is the correct one to use here. I think the one in the picture is a Lin/log converter. I think I need a log/lin converter. I am not sure how to do that.

Here is an update to help you build a roland sh101 type of filter. These guys did the hard part of figuring out what the resistor values are to replace the BA obsolete chip with Discrete components: http://mutable-instruments.net/shruthi1/build/smr4mkII. There is a schematic at there website.

Hey not sure if you're on the SDIY facebook group. But I have done it and yes, it is totally possible.

I have some real IR3109s and with advice from guys on the SDIY mailing list I figured out the internal resistor values between the gain cells non-inverting inputs and ground as 432 ohms.

I used one LM13700 to make a 12db version of this filter
For the expo converter I used the standard Thomas Henry current source type. The thing I haven't figured out is the buffers between the gain cells. I used a TL072 in my circuit but next im going to try a FET as it's what Roland preffered to use.

I'm not aware of the calculation here, but has anyone a schematic for -/+12v or an explication note?
I want to know how this thing is acting like the IR3109, I must try to breadboard from discreet and LM31700...

just finished that above mentioned 121 VCF and hmmm... i'm not so glad with my result... i have used 2xLM13700 and 4x 2SK30 instead of the original parts...

the filter does self oscillate but only in the very low spectrum and the Output is rather a square than a sine... even with no Input at Audio in...

tried playing aroud with the resistors in the Feedback path of resonance...
reducing that 6,8k resistor even lowered the frequency so i thougth ok let's increase it... so i soldered a 4,7k with a 10k trimmer in series and well it's slightly higher and the resonance Output is lower in Amplitude but i only get more of a humming frequency and when i only had 68k in self oscillation disappeared...

any idea how it's original behaviour is?
does it cover a wider range of frequencies in self oscillation?
any Information or Input would be welcome as usual... thank you_________________https://soundcloud.com/bastian-j

just finished that above mentioned 121 VCF and hmmm... i'm not so glad with my result... i have used 2xLM13700 and 4x 2SK30 instead of the original parts...

the filter does self oscillate but only in the very low spectrum and the Output is rather a square than a sine... even with no Input at Audio in...

tried playing aroud with the resistors in the Feedback path of resonance...
reducing that 6,8k resistor even lowered the frequency so i thougth ok let's increase it... so i soldered a 4,7k with a 10k trimmer in series and well it's slightly higher and the resonance Output is lower in Amplitude but i only get more of a humming frequency and when i only had 68k in self oscillation disappeared...

any idea how it's original behaviour is?
does it cover a wider range of frequencies in self oscillation?
any Information or Input would be welcome as usual... thank you

something must be wrong with your build. i am getting a very nice sine wave across the whole spectrum:

Hi Roglok,
thanks for your reply.
Have soldered the FET according to the SK30 data sheet i found at my suppliers pages.
These are as per front view (where you can read the identifier) from left to right source, gate and drain...

and when i read the original schematic correct, then there is the gate connected to the Output of the OTA the source to +15V and the drain goes to the next stage and -15V via resistor. correct?

Problem fixed...
Forgot to cut two rails on my stripboard design so that the gates and drains of the FET's between stage 2 and 3 where tied together... luckily nothing blew up and i have now a sine over the whole spectrum with full resonance and the filter sounds like a filter know and not only like an VCA turning tone on and off...

will now tweak and tune it a bit until i'm satisfied...

should consult my doctor and check my eyes as i have checked the layout a few times but always missed that failure... _________________https://soundcloud.com/bastian-j

hm... i've always built all my modules on stripboard... so far 4 cases of 48x35 cm filled with 79 modules are filled...
most competing modules where so far the serge vcadsr and serge vcs and the mfos quantizer...

i mostly use the normal 100x160 mm stripboards... just a very few use the 100x200 mm ones...

can you give me a hint and a link to some good Freeware stripboard layouter? otherwise i could draw it on paper and then scan it... but i think that could be hardly to read...

i also have to say that i used lm13700 and 2sk30 so that this layout is limited to them or equivalent pin compatible stuff (LM13600 would work too)

i maybe start when i have finished replacing two older simple AR-Generators with Ian's AD/AR and Delayed Pulser... just have to twaek it a bit for another LED for the Envelope and include two Switches for different Timings as there are already some holes in my case from the previous modules...

hm... i've always built all my modules on stripboard... so far 4 cases of 48x35 cm filled with 79 modules are filled...
most competing modules where so far the serge vcadsr and serge vcs and the mfos quantizer...

i mostly use the normal 100x160 mm stripboards... just a very few use the 100x200 mm ones...

can you give me a hint and a link to some good Freeware stripboard layouter? otherwise i could draw it on paper and then scan it... but i think that could be hardly to read...

i also have to say that i used lm13700 and 2sk30 so that this layout is limited to them or equivalent pin compatible stuff (LM13600 would work too)

i maybe start when i have finished replacing two older simple AR-Generators with Ian's AD/AR and Delayed Pulser... just have to twaek it a bit for another LED for the Envelope and include two Switches for different Timings as there are already some holes in my case from the previous modules...

ah nearly forgot it... most important and maybe of interest it's not the SH101 VCF that i've built it's the System 100 121 VCF...
but both are using 4 OTA stages... so i think they are somewhat comparable...
Here's a link to most of the Roland VCF schematics:
http://fa.utfs.org/diy/roland_filters/

thank you very much my friend
i've attached a simple program called DIY layout creator.
its very simple to work with
thank again my friend!

The Program doesn't run on my PC... after installing and trying to open it always two failure reports occur...
tried googling for another Version and downloaded... that one runs but i think it's way to complicated to draw that all with this program..

I think i'll be much faster with drawing it on paper (squared paper or wathever it'S called) and scan that together with some photos guess that will be easier and much faster...

Just had a few minutes at work left to figure out some things on the Version i downloaded and installed...
seems as most things i could need i'm able to draw them but one Thing i haven't figured out yet... how can i bend a leg of a Transistor...
mean normally you have them in a straight row or triangle

o e
o b
o c

o e
xo b
o c

the o's here are the legs and the x is a cut trace/hole

i wan't to know how i can bend them that it's like below

o emitter
o base
x or other trace
o collector

is this possible? if so how?

anyway this Programm seems better as i first thougth of it... must get rid of my fear about new technoligies... _________________https://soundcloud.com/bastian-j

the White dots mark where the trace has to be cut on the side with copper rails... indeed also cuts are needed underneath the IC's...
the black dots mark the Points for external wiring... not shown frequency pot which needs +15V and GND on it's outer wipers... also not shown Input attentuators for Signal and CV...

All Electrolytic caps except those 2 on the power rails should be non-polarized as per Frequency Central...
btw. in the schemo i see BP which for me would mean Bipolar... hmm... for non-polarized i'd expected a NP

because lacking a sdt-1000 i used a 2,2k NTC and a 8,2k to 10k resistor in series (that's the one mislabeled with 1k)

Before building please take Care of the Veroboard Size... i guess i missed a bit the Ratio... but everything should fit easily on a 2,5mm raster on a 100x160mm board

would be nice if someone could check if i missed something... maybe i'll do that later...

P.S. tried to upload the diy layout creator file as well... but this doesn't seem to work... restricted file extension

Edit says: like in my first own build i forgot to cut a trace... please do cut between both drain of the FETs between stage 2 and 3

that was the original schematic attached in the 121 VCf clone pdf from frequency central... see above in this thread...

just figured out the Pins of the LM13700 vs Ba662 and then going for it..

i have to tell that ialso tried to mod this with a small passive hpf via Rotary swith and different cap sizes... works not as well as thought first... it's more lowering the volume than filtering higher frequencies out...

edited that in my previous post too... have spotted the first mistake... both drains between FEt 2 and 3 should be separated... the same i've forgotten in my first own build... i knew someone, who can endlessy repeat the same stupid mistake... _________________https://soundcloud.com/bastian-j

thanks to Roglok for providing the link to the wonderful Roland SH 101 filter revision by Frequency Central.
My question is, may i subb in any general op-amp in place of the specified lf 351 ? And can i use the lm 13700 in place of the 3080 safely?

i attached a part of the schematics. May i assume that the red arrow is pointing to the audio input?
and what's the symbol the green arrow is pointing to?

Someone tried to stripboard the filter but i havent heard about the results.

You cannot post new topics in this forumYou cannot reply to topics in this forumYou cannot edit your posts in this forumYou cannot delete your posts in this forumYou cannot vote in polls in this forumYou cannot attach files in this forumYou can download files in this forum

Please support our site. If you click through and buy from our affiliate partners, we earn a small commission.